2021 IRC Chapter 40
This lesson covers the devices GCHS staff see and touch every day in a finished house: the switches, receptacles, and light fixtures on the wall and ceiling. Most of the numbers here are about keeping people safe around water, keeping small children from shock and burn injuries, and keeping heat-producing fixtures away from combustible storage. Lesson 6 covered where GFCI and AFCI protection is required; this lesson covers the devices themselves and where luminaires may and may not go.
E3903.2 requires at least one lighting outlet controlled by a listed wall-mounted control device, in practice a wall switch, in every habitable room, kitchen, and bathroom, located near an entrance to the room. In rooms other than kitchens and bathrooms, one or more switch-controlled receptacles may stand in for the lighting outlet, but kitchens and bathrooms need a true lighting outlet. E3903.3 adds hallways, stairways, attached garages, and detached garages with power, plus a lighting outlet on the outside of each grade-level outdoor egress door. Where an interior stairway has six or more risers between floor levels, E3903.3.1 requires a control at each floor level and landing level that includes an entryway, so a person is never caught on a dark stair with the only switch at the far end. E3903.4 covers attics, underfloor spaces, utility rooms, and basements: at least one lighting outlet is required where the space is used for storage or contains equipment needing service, a furnace or water heater for example, with a point of control at each entry, and an outlet serving equipment goes at or near that equipment.
A snap switch must interrupt the ungrounded, or hot, conductor, never the grounded (neutral) conductor (E4001.8, E4001.9). Switching the neutral leaves the fixture's socket shell and internal wiring energized even with the switch in the off position, a hazard discovered the hard way by whoever next changes a bulb. The switch must be listed and used within its ratings (E4001.1): an ampere rating not less than the load it controls, and suitability for the type of load. A switch rated for lighting is not necessarily suitable for a motor load, which may not exceed 80 percent of the switch rating, since motors draw a locked-rotor inrush current far above their running current every time they start. E4001.15 also requires the grounded (neutral) conductor to be installed at switch locations that control lighting in bathrooms, hallways, stairways, and habitable rooms, even where the switch itself does not use it, with exceptions such as a box where a cable can be added without removing finish materials, conductors entering through a raceway large enough for a neutral, or lighting under automatic control. The neutral means electronic devices such as occupancy sensors, timers, and smart switches installed later have a neutral available to power themselves rather than leaking a small standby current through the equipment grounding conductor, which is not what that conductor is for.
A three-way switching arrangement, two switches controlling one luminaire from two locations, uses three conductors between the switches: two travelers and the conductor that carries the fixture current. Each switch has one common terminal, distinguished by color from the two traveler terminals; the common terminal at the switch nearest the source receives the incoming line, and the common terminal at the switch nearest the luminaire sends the switch leg out to the fixture, with the travelers running between the two switches' traveler terminals. Landing a traveler on a common terminal, or the reverse, is the classic wiring error that makes a three-way switch work from one location but not the other.
IRC E4002.14 (NEC 406.12) requires listed tamper-resistant (TR) receptacles for the 15- and 20-ampere, 125- and 250-volt nonlocking receptacles in the areas that need receptacle outlets under E3901.1, which in a dwelling means essentially every such receptacle, not merely rooms thought of as children's spaces. A TR receptacle uses internal shutters that open only when both slots are engaged simultaneously, the way a plug's two blades do, so a single object such as a hairpin or key pushed into one slot alone cannot open the shutters. The requirement targets a well-documented pattern of child shock and burn injuries from objects pushed into ordinary receptacles. The exceptions are narrow: receptacles located more than 5 1/2 feet above the floor, receptacles that are part of a luminaire or appliance, and a single receptacle for one appliance or a duplex receptacle for two appliances in spaces dedicated to appliances that are not easily moved.
An outdoor receptacle in a location exposed to direct rain or hose spray is a wet location. Under E4002.9 it requires a weather-resistant (WR) receptacle along with an in-use, or bubble, cover that keeps the receptacle weatherproof whether or not a cord is plugged in, and the cover hood must be the listed extra-duty type for 15- and 20-ampere receptacles, since ordinary plastic lids crack after a season or two of sun and cold. A receptacle under a roofed, open porch, protected from direct rain and runoff but exposed to blowing moisture, is a damp location (E4002.8): it still needs a WR receptacle and a weatherproof cover, but that cover only has to protect the receptacle when no plug is inserted, since the location is not expected to see a cord left plugged in through driving rain. Outdoor receptacles, wet or damp, also require GFCI protection (E3902.3), covered fully in Lesson 6; a WR listing and GFCI protection are two separate requirements that both apply, one does not substitute for the other.
Under E4002.11, a receptacle may not be installed within a zone measured 3 feet horizontally and 8 feet vertically from the top of the bathtub rim or shower stall threshold. The zone is all-encompassing and includes the space directly over the tub or shower, replacing older wording that only prohibited receptacles within or directly over the tub. A receptacle 2 feet horizontally from a tub rim and 4 feet above the floor falls inside that zone and is not permitted there regardless of GFCI protection; GFCI protection is required everywhere in the bathroom under Lesson 6's rules, but it does not create an exception to the zone's physical placement restriction. The one exception is a bathroom too small to leave any space outside the zone: there the receptacle may be placed on the farthest wall in the room, opposite the tub rim or shower threshold.
A faceplate is required to completely cover the wall opening and seat against the wall surface (E4001.11, E4002.5); a missing faceplate at final inspection is not a cosmetic item; it exposes energized terminal screws at exactly the height a child's hand or a mop handle reaches, and leaves an opening into the wall cavity. A metal faceplate on a snap switch or receptacle must be connected to an equipment grounding conductor, normally through the device's mounting yoke, so an internal fault trips the breaker rather than energizing a touchable metal plate; for a replacement switch on old wiring with no equipment grounding conductor, E4001.11.1 allows an ungrounded switch with a nonconducting faceplate and nonmetallic screws where it is within 8 feet vertically or 5 feet horizontally of grounded objects, unless the yoke is nonmetallic or the circuit is GFCI protected. A device recessed behind the finished wall surface with no spacer flexes at its terminations every time a cord is plugged in and unplugged; box extenders or listed spacers bring the yoke out to properly bear against the wall.
The "storage space" in a clothes closet, for luminaire clearance purposes (E4003.12), runs from the floor up to 6 feet or the highest clothes rod, whichever is greater, extending 24 inches horizontally from the side and back walls, then continues up to the ceiling at a distance of 12 inches or the shelf depth, whichever is greater. Within that storage space, or too close to it, heat-producing fixtures are tightly restricted: a surface-mounted fixture with a completely enclosed incandescent or LED source needs 12 inches of clearance from the storage space, a recessed fixture or a surface-mounted fluorescent fixture needs 6 inches, and any luminaire with an open or partially enclosed lamp, the classic bare pull-chain bulb, as well as any pendant luminaire or lampholder, is prohibited in a clothes closet outright, regardless of clearance, because a bare incandescent lamp runs hot enough to ignite fabric it contacts. Only a surface-mounted fluorescent or LED luminaire specifically identified for the purpose may be installed within the storage space itself.
A recessed luminaire marked "IC" is evaluated for direct contact with thermal insulation, the practical requirement in a modern, heavily insulated attic where blown-in or batt insulation is expected to bury the housing. A non-IC-rated recessed housing instead needs thermal insulation kept off the top of the housing and at least 3 inches from its enclosure and wiring compartment (E4004.9), and 1/2 inch of clearance from combustible material generally, except at its points of support and trim (E4004.8); burying a non-IC can in insulation cycles its internal thermal protector on and off and chars the surrounding material over time, a defect GCHS finds regularly in attics that were insulated or re-insulated after the original electrical work.
The same 3-foot horizontal, 8-foot vertical zone that restricts receptacles near a tub or shower also restricts luminaires: pendants, cord-connected, chain-, cable-, and cord-suspended fixtures, track lighting, and paddle fans are all excluded from that zone outright (E4003.11), because a bather standing in the tub, wet-skinned and in contact with grounded plumbing, is far more likely to suffer a fatal shock from contact with an energized fixture than a person standing on a dry floor elsewhere in the house. A luminaire located within the actual outside dimensions of the tub or shower, up to 8 feet above the rim or threshold, must be marked for damp locations, and marked for wet locations where it is subject to shower spray; a recessed fixture is the usual way to meet this. Lighting track is separately restricted (E4005.4) from being installed where concealed, extended through a wall or partition, or in a damp or wet location, and it must be at least 5 feet above the floor unless protected from damage or operating below 30 volts. Track is an exposed, field-configurable busway whose connections were never evaluated for being hidden.
An ordinary outlet box is evaluated to support up to 50 pounds hanging from it (E3905.6.2); a heavier fixture needs independent structural support, a strap or bar hanger fastened to framing, or a box carrying a listing for the greater weight. A ceiling paddle fan is a special case regardless of its weight: fans impose a dynamic, oscillating load an ordinary luminaire box was never evaluated for, so a fan that hangs from an outlet box must use a box or box system marked as suitable for fan support, or else be supported independently of the box (E3905.8, E4101.6). In a habitable room, a ceiling box where a fan could later go must be fan-rated or give access to framing that can carry a fan bracket. Once a fan exceeds 35 pounds, the supporting box must additionally be marked with the maximum weight it supports, and 70 pounds is the practical ceiling for a fan supported by an outlet box at all; heavier fans are supported independently of any box.
A worked example on required receptacle spacing tying back to Lesson 5: a living room wall runs 18 feet with no break for a doorway. Under the 6-foot rule, no point along that wall may be more than 6 feet from a receptacle outlet, so consecutive receptacles can be no more than 12 feet apart (6 feet on each side of a receptacle), and each end of the wall no more than 6 feet from the nearest one. Two receptacles at roughly 6 and 12 feet along the wall meet the rule; a third is a convenience, not a requirement.
In the field
On a bathroom remodel, GCHS checks four things at the vanity and tub area together: is the new receptacle outside the 3-foot horizontal, 8-foot vertical tub and shower zone, is it GFCI protected, is any light fixture within the tub or shower footprint marked for damp locations (wet if subject to spray), and is any switch inside the wet location of the tub or shower space excluded unless it is part of a listed tub or shower assembly (E4001.7). Missing any one of the four is a common and completely avoidable finding at final.
1. Tamper-resistant receptacles are required in a dwelling:
2. A receptacle installed outdoors in a wet location requires:
3. Which fixture is permitted within the 3-foot horizontal, 8-foot vertical zone around a bathtub (E4003.11)?
4. Under E4002.11, in a bathroom with room outside the zone, a receptacle 2 feet horizontally from a bathtub rim and 4 feet above the floor is:
5. A surface-mounted, completely enclosed incandescent or LED luminaire in a clothes closet must keep what minimum clearance from the storage space?
6. From the closet floor up to 6 feet or the highest hanging rod, the "storage space" in a clothes closet extends horizontally from the side and back walls a distance of:
7. A recessed luminaire marked "IC" is one that is:
8. Under current code, GFCI protection for a dwelling dishwasher is:
9. A ceiling paddle fan that hangs from an outlet box needs:
10. A luminaire weighing 65 pounds is proposed for an existing ordinary ceiling outlet box. The correct approach is:
11. A switch controlling a bathroom light is installed inside the wet area of the shower itself. This is:
12. The correct arrangement for a switched luminaire in a dwelling is that the switch interrupts:
13. A dimmer is installed to control a ceiling paddle fan's motor speed. This is:
14. A cover plate is missing from a receptacle at final inspection. This is: